Skip the auto shop - Our mechanics make house calls

Q: Engine puffs blue smoke; thumping noise at highway speeds

asked by on

In the mornings when I start my SUV, for a few seconds the engine puffs blue smoke. When I’m driving on the highway at 60 mph, it begins to make a very obnoxious thumping sound that can also be felt by the vibrations. It feels like there is something stuck to the tire, but when I examine them, I don’t find anything. With more speed, the louder it becomes. I have looked at the transmission, driveline, shafts - all seem fine. Another problem is that when I am braking, the steering wheel shakes and there is a loud noise under the brake pedal. I have already changed the brake pads and the rotors, machined them, etc. No repairs have worked! I would greatly appreciate your advice on what will fix my car. Thanks.

A: Hi there, thanks for asking about your 2004...

Hi there, thanks for asking about your 2004 Infiniti FX45. The blue smoke you notice on initial start-up is likely caused by worn exhaust valve stem seals. They allow a tiny amount of oil to get into the combustion chamber while the car sits overnight. This will slowly get worse with additional miles until the valve stem seals are replaced. Have the front tires and wheels checked for balance, "roundness", or any separation of the tread of the tire at a reputable tire dealer. There is likely something amiss that's showing up at highway speed and under braking. If you want to have this checked by a certified mechanic, a technician from YourMechanic can come to your home or office to inspect the smoke coming from your car's exhaust.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Car shudders during hard braking

More than likely, your brake rotors are warped. Warped rotors result in a vibration that can be felt in the steering wheel and/or brake pedal. A standard brake job with new pads and new or machined rotors (depending on the...

Q: Check engine light/emissions workshop! blowing black smoke while accelarating, among other acceleration issues.

Hello. Black smoke is usually the result of an excessively rich condition. The black smoke is a result of excessive fuel from a rich condition that was not burned in the combustion chamber, burning up afterwards, in the exhaust pipe,...

Q: Despite repairs, vibrations and droning noise persist - 1997 Ford Aerostar

Hello. With the information I have, it sounds like there could be an issue with the rear differential of your van. A droning noise from the rear could be caused by one of the wheel bearings, or the carrier bearings...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.